Imidazolidine-2-thione derivatives



United States Patent Ofiice 3,313,788 Patented Apr. 11, 1967 3 313 788 IMIDAZOLIDINEi-THIONE DERIVATIVES Lucien Convert, Thiais, and Raymond Fabre, Vincennes,

France, assignors to Rhone-Poulenc S.A., Paris, France,

a French corporation N Drawing. Filed Dec. 31, 1964, Ser. No. 422,527

Claims priority, application France, July 18, 1964, 982 205 7 Claims. 61. 260-795) with metal oxides alone such, for example, as the oxides of zinc, magnesium, and lead, or with mixed such oxides. However, under these conditionsvulcanization progresses slowly and is incomplete so that the vulcanizates obtained have unsatisfactory technical properties.

On the other hand, it is known that the use of classic vulcanization accelerators, either by themselves or in mixtures, such as the guanidines and the thiurams, raises the vulcanization speed and improves the characteristic properties of the vulcanizates, but these accelerators are still incapable of achieving the desired level of vulcanization.

Other, more specific accelerators, have been suggested for the vulcanization of mixes containing chloroprene polymers, especially imidazolidine-Z-thione, alkylated or cycloalkylated thioureas, triazine derivatives, thiosemicarbazides, thioxamides and cyclic polyamides.

The use of some of these compounds improves the properties of the vulcanizates substantially, but, quite frequently, this is accompanied by a lesser facility and safety in the handling of the mixes prior to vulcanization. Users in fact know very Well the tendency of mixes, especially those which contain a thiourea, to undergo prevulcanization. Inconveniences of this kind may occur in the course of the diverse operations involved in the processing of the mix prior to vulcanization, and this may sometimes result in very appreciable losses of material.

It has now been found that the derivatives of imidazolidine-Z-thione of the general formula:

where R and R are identical or different and each represents hydrogen, lower alkyl, cycloalkyl, or hydroxymethyl, A represents a saturated, straight or branched hydrocarbon residue, and R 'and R are identical or difierent and each represents hydro-gen, lower alkyl, or cycloalkyl, or -NR ANR represents CHCH where the R radicals are hydrogen or methyl, and are not necessarily the same, are accelerators of special value for vulcanizing mixes based on a polychloroprene or a chloroprene copolymer. The lower alkyl radicals referred to contain from 1 to 5 carbon atoms, and include, more especially, the methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl radicals. The cycloalkyl radicals are preferably mononuclear cycloalkyl radicals whose ring contains more than 4 carbon atoms, which may be substituted, especially by lower alkyl groups, such as methyl or ethyl. Specifically, there may be mentioned the cyclopentyl, the cyclohexyl and the cyclooctyl radicals. The chain A may be, for example, ethylene, trimethylene, tetramethylene, pentamethylene or hexamethylene.

The most valuable residues of the formula:

are those derived from piperazine and 2,5-dimethyl-piperazine.

According to a feature of the invention, the compounds of Formula I are prepared by reacting two mols of an imidazolidine-Z-thione of formula:

if s (II) (or mixtures thereof) with one mol of an amine of forand two or more mols of formaldehyde. This process may be operated in a variety of ways, as follows:

(1) Two mols of formaldehyde are first reacted with one mol of an amine of the general formula:

and the N,N'-di-hydroxymethyl derivative of the said amine obtained is then reacted with two mols of an imidazolidine-Z-thione of Formula II or with a mixture of such compounds.

(2) Two mols of formaldehyde are reacted with two mols of the imidazolidine-Z-thione of Formula II to form the corresponding N-hydroxymethyl compound and this is then reacted with one mol of an amine of the formula (3) When R and R represent CH OH residues, four mols of formaldehyde are reacted with 2 mols of imidazolidine-Z-thione to form the corresponding N,N-bis(hydroxymethyl) compound, and this is then reacted with one mol of an amine of formula The process described above can be performed at room temperature (i.e. about 20 C.) or with moderate heatmg.

The compound of the Formula I can be used as accelerators for the vulcanization of chloroprene polymers, such as homopolymers of chloroprene and copolymers containing at least 40% of chloroprene residues, and obtained by copolymerizing chloroprene with one or more co-monomers such as acrylonitrile, butadiene, isoprene, dichloro-2,3-butadiene and styrene. The manufacture of chloroprene polymers of this type has been described in various publications, especially in fSynthetic Rubber, John Wiley & Son, Publishers, New York, pp. 767 to 793 [1954].

The new accelerators can be used in amounts depending on the type of polymer to be vulcanized, on the mix to be treated, and on the special result desired. In general an amount ranging from 0.5 to 5 parts per parts by weight of chloroprene polymer is used.

The new accelerators may be used with any usual mix containing a chloroprene polymer. It is known that these compositions generally contain as vulcanizing agents certain metal oxides (e.g. the oxides of zinc, magnesium or lead). It is also possible to add black reinforcing agents and diverse additives, such as peptizin-g agents, usual or EXAMPLE 2 special antioxidants, coloring matter and/ or plasticizers. The incorporation of the accelerator in the mix may be carried out by conventional methods at any stage before the mix reaches the vulcanizing temperature. The han- 5 According to the method described in Example 1, but using 360 cc. (4 mols) of 30% formalin per mol of piperazine, the product of the following formula is obdling of the accelerators of this new type is facilitated by tamed the fact that the crude mixes have a thermostability far H2G" CHZ H20 superior to that of any product used in the past, and this HOHzC-N NOH -N NCIIz-N N-CHZOH enhanced stability does not in any way affect the vul- GHPCHI canizing speed at the temperature at which vulcanization 1] u is carried out, usually 120 to 200 C. s O

Unvulcanized mixes containing one or more of the com- (=product C, used below). gglrllnds of Formula I are within the scope of the mven EXAMPLE 3 The vulcanizates of this invention possess good general The following 5 mixes are prepared in a roller mill: properties. Their surface is perfect, which is not always TABLE 1 the case with known accelerators.

The following examples illustrate the invention. Mix

EXAMPLE 1 1 2 a 4 5 A round-bottom flask provided with a mechanical stiren%%5fif if??? rer is charged with 204 g. (2 mols) of imidazolidine-2- g g3e7igflaphthylamind thione and 2 liters of water, the temperature being C. Zinc Dime 111:1111" 180 cc. (2 mols) of a formalin solution are then gi gggg is added gradually within 1 hour. When all has dissolved, Product 13:: a solution of 86 g. (1 mol) of anhydrous piperazine in Product 0 550 cc. of water is rapidly added. The batch is heated to 30 C. in the course of 30 minutes and then to 50 C. 30 1 Known accelerator used for companson' within 3 hours, then cooled to 20 C. and the solid mate- Each of these 5 mixes is measured for the scorching rial formed is isolated, washed and dried under vacuum. time according to Mooney and then vulcanized in moulds Yield: 290 g. (=92.4% of theory). in a press at 153 C. The scorching times and proper- The product, which melts above 300 C. with decomties of the vulcanizes are shown in the following table:

TABLE 2 scorching time according to Characteristics after vulcanization Mooney plus 10 in minutes Vulcanizing Mix at C.- time in minutes Rupture, Modulus Elonga- Shore Appearance of 121 130 150 kglcm. 600%, tionin hardness surface l-:g./crn. percent A 1 60 No vulcanization after 60 minutes 20 190 52 810 42 Slightly granular. 3 it 2? 23 it 1 0 0 0 189 73 725 47 20 184 as 725 46 DO 40 171 83 700 49 20 200 42 835 42 D0 40 171 64 755 (a) Mooney value immediately after preparing the mix. (b) Mooney value after 15 days storage.

position, is identified by analysis as having the following EXAMPLE 4 formula: The following 5 mixes are prepared under the usual H2O CH1 CH2CH2 H2C-OH3 conditions in a Banbury internal mixer, the accelerators HN NH being added afterwards in a roller mixer.

H CHr-OHa J TABLE 3 5 Mix (=product A, used in the following examples).

In the same manner, but replacing piperazine by di- 1 2 3 4 5 methyl-2,5-piperazine, the compound of the following ford b Ingre ients parts yweightl: mula' 18 p p I Neoprene W CH3 Stearic aeid I 1lsllack Sem1-remforc1ng, furnace) agnesra H2C-'CH2 CH CH2 I HzC CH: %m% 2 fi: n11 azo me lone HN\ /N CH2N N c a-N\ /NH g g gig lO 1.10 (I? GHg-OH Product C S CH2: 5

(=product B, used below). This compound likewise Each of these 5 mixes is measured for the scorching melts above 300 C. with decomposition. time according to Mooney and then vulcanized in moulds ma press at 153 C. The scorching times and properties of the -vulcanizates are shown in the following table:

represents a saturated hydrocargon residue, and R and R are each selected from the class consisting of hydro- TABLE 4 Scorching time according to Characteristics after vulcanization Mooney in minutes at C.

' Vulcanizing Mix time in minutes Rupture, Modulus Elonga- Shore 110 121 130 kgJcm. 200%, tion in hardness kg./cm. percent A 129 37 620 9 6 6% 20 204 405 63 40 208 83 360 63 3 (a) 24% 15% 20 212 70 490 62 40 210 84 390 64 4 (a) 18% 12 20 201 415 64 40 202 370 62 5 (a) 19% 12% 20' 204 56 480 61 40 203 74 390 62 (a) Mooney value immediately after preparing the mix.

EXAMPLE 5 The following 5 mixes are prepared under the usual gen, lower alkyl, and cycloalkyl, and NR ANR may additionally represent conditions in a Banbury internal mixer, the accelerators R B being incorporated afterwards in a roller mixer. 8 1 TABLE 5 N\ N1.- Mlx 30 (|JH(|J R R 1 2 3 4 5 Ingredients (parts by Weight): where the R radicals are each selected from the class con- NeopreueW 100 100 100 100 sistmg of hydrogen and methyl. iiii fi 'imaann..- II::: Z8 'Z3 35 2. A compound as claimed in claim 1, in which R and Black (easy processing channel)". 20 0 R are each selected from the class consisting of hydroggg gj f 2 gen and hydroxymethyl, and --NR -A--NR is se- Zinc oxide, 5 lected from the class consisting Imidazolidinehinnp groguez ['0 11C Product O CH3 G s-CH: H-CH2 Each of these 5 mixes is measured for the scorching and time according to Mooney and then vulcanized in a mould g g 0 0 2-0 2 CHz-C m a press at 153 C. The scorching time and the prop- 45 erties of the vulcanizates are shown in the following table: 0H3

TABLE 6 scorching time according to Characteristics after vulcanization Mooney plus 10 in minutes Vulcanizing Mix at 0. time in minutes Rupture, Modulus Elonga- Shore kgJcm. tion in hardness 121 kg./cm. percent A (a) Mooney value immediately after preparing the mix. (b) Mooney value after 15 days storage.

We claim: 1. A compound of the formula: 3. The compound of formula:

Hz?CHg HgC CH2 R -N C-CH -N-A-N-CHz-N N-H; 70

C R O/ 2(l3-C 2 GEE-CH1 H1CCH2 3 4 HN N-OHz-N N-CHz-N NH s s O CH2-OH2 C where R and R each selected from the class consisting of g g hydrogen, lower alkyl, cycloalkyl and hydroxymethyl, A 75 7 4. The compound of formula:

CH3 Hz0-GH, |CH-CH2 H2CGH;; Hl T N-CHz-N N-CHz-N NH O CH2OH G 5. The compound of formula:

HzC-CH2 GHQ-CH2 HzC CH2 HOH2CN NCHaN N--CHz-N N-OHzOH 0 CHz-CHa 0 t t 6. A vulcanizable mix comprising a polychloroprene or chloroprene copolymer and, as vulcanization accelerator, at least one compound of the formula 8 where R and R are each selected from the class consisting of hydrogen, lower alkyl, cycloalkyl and hydroxymethyl, A represents a saturated hydrocarbon residue, and R and R are each selected from the class consisting of hydrogen, lower alkyl, and cycloalkyl, and

-NR -ANR may additionally represent 5 i /CH-CH N (IE-(3H R R where the R radicals are each selected from the class consisting of hydrogen and methyl.

7. Process for producing a vulcanizate which comprises heating a mix as claimed in claim 6.

No references cited.

JOSEPH L. SCHOFER, Primary Examiner.

D. K. DENNENBERG, Assistant Examiner. 

6. A VULCANIZABLE MIX COMPRISING A POLYCHOLROPRENE OR CHLOROPRENE COPOLYMER AND, AS VULCANIZAITON ACCELERATOR, AT LEAST ONE COMPOUND OF THE FORMULA 